It is known to provide motor vehicles with Adaptive Cruise Control (ACC) which is operable to adjust the cruising speed of the subject vehicle to respond to traffic conditions. For example, the ACC can reduce the vehicle speed as the subject vehicle approaches a vehicle travelling slower than a cruise speed specified by the driver. When the driver pulls out from behind the slower vehicle, the ACC will automatically accelerate to resume the specified speed. A radar tracking system is typically provided to track object vehicles and provide control data to the ACC.
A desired feature of ACC is that the resumption to the specified speed starts quickly when the driver starts to pull out. However, there can be a delay before the radar can determine that the road ahead is clear and, therefore, initiation of the vehicle acceleration may be delayed. A typical pathway P for a vehicle operating in this mode is illustrated in FIG. 1A.
To reduce any such delay, it is known to use indicator information to initiate an acceleration surge (also referred to as indicator surge) when the driver indicates to pull out. When the driver operates the vehicle indicators to signal a manoeuvre, the vehicle automatically accelerates. If the driver does not subsequently pull out, the vehicle will slow again and return to its normal follow distance after a few seconds. If the driver proceeds with the manoeuvre, any delay in returning to the set cruise speed is minimised as the vehicle is already accelerating. A typical pathway P for a vehicle operating in this mode is illustrated in FIG. 1B.
One disadvantage of this technique is that when indicating to take an exit ramp from a highway (to the left in regions such as the UK having left-hand traffic), the same acceleration surge function will be triggered, as illustrated by the vehicle pathway P in FIG. 2. The resulting increase in the vehicle speed can prove disconcerting in these circumstances. To address this, the acceleration surge function could be keyed to the hand of traffic of the vehicle (i.e. right-hand traffic, or left-hand traffic) based on its home market. However, any such keyed response would become incorrect if the vehicle is taken out of market (e.g. if a UK car is driven on the continent).
The present invention sets out to address at least some of the shortcomings associated with prior art systems.